The formation of junctions between metal and plastic is useful for a variety of applications. Currently, the most common way to form a junction between metal and plastic is using glue. For instance, for an extrusion lamination application, the glue layer is placed between the metal and the plastic. However, glue presents cost, toxicity, weight, and environmental concerns, Sometimes, a secondary operation is needed to cut out excess un-needed dried glue. In addition, the application and curing of glue consumes time. For in-mold injection molding, chemical etching of metal surface is sometimes used. However, some types of plastic resins are not compatible with chemical etching methods, and chemical etching can generate a limited variety of surface features on the metal. Also, chemical etching cannot easily provide localized or patterned treatment of the metal surface.
During formation of junctions between plastic and metal, the metal part is first cut by machining, with subsequent treatment of the metal surface in a separate step to prepare it for joining to the plastic.